Multichannel magnetic transducers are known to be utilized for recording simultaneously a number of parallel tracks on a magnetic medium, each channel recording one track. For example, a set of tracks consisting of a fixed number of n parallel tracks may be recorded on a magnetic medium simultaneously during a single scan of a rotating multichannel transducer. By "scan" there is understood a passage or swipe of a rotating multichannel transducer over a magnetic medium for simultaneously recording or reproducing signals with respect to parallel tracks on the medium. For proper reproduction of the information content recorded, each such set of tracks must be accessed simultaneously by a corresponding multichannel transducer for playback. For the purpose of this description it will be further referred to a position of a playback multichannel transducer over a set of simultaneously recorded tracks as "home track position."
Known tracking systems in helical scan tape recording/playback devices utilize a pilot tone which is added to the information signal and recorded. The pilot tone is phase shifted on successive tracks by a known phase angle, for example by 90 degrees. During playback the pilot tone is separated from the information signal and applied as tracking information to a tracking servo. A phase comparator compares the reproduced pilot tone with a reference signal and the resulting phase error signal is applied to the tracking servo to correct for mistracking. While this circuit provides adequate tracking information when the multichannel head is within the home track position with an offset not exceeding one-half of a track width in either direction, reliable tracking information is not obtained outside that range. Because of the low signal-to-noise ratio obtained outside that range, the beginning of the reproduced data from each track cannot be reliably detected. Therefore, a pilot tone reference signal cannot be reliably initialized as is necessary at the beginning of each scan. It is therefore desirable to obtain a proper reference for acquiring home track position without utilizing the pilot tone.